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Identifies a cell surface protein of the immunoglobulin superfamily expressed on follicular helper T cells, activated T cells, B cells, and myeloid cells. PD-1 highlights TFH cells in germinal centers and is a useful diagnostic marker for TFH-derived T-cell lymphomas, including angioimmunoblastic T-cell lymphoma. Because it stains few B cells, PD-1 offers improved specificity in this setting. PD-1 is also a key target of emerging immunotherapies.
Tissue Block: Formalin-fixed, paraffin-embedded (FFPE) tumor block preferred.
Unstained Slides: Recommended 2 charged slides per stain requested (minimum of 1 slide per stain), baked or unbaked.
Fixation: Tissue must be fixed in 10% neutral buffered formalin for 6–72 hours.
Use cold pack for transport. Make sure cold pack is not indirect contact with specimen.